Any polish has the potential to fill, that's why you should always use an IPA wipedown to inspect for filling. But IME, D300 does what it claims and in some cases you can go straight to LSP without needing a finishing step. That all depends on paint hardness and technique though. The real game changers are the MF pads. Use them with D300, 105, 205, Menz polishes, whatever. They work incredibly well for cutting. For finishing on multi-steps, I still prefer foam though.